Fox sued Carnahan, a Democrat running for U.S. Senate, in Kansas City Federal Court on Wednesday, claiming one of her TV ads smearing Republican incumbent Roy Blunt violated the network’s copyrights. Fox says the ad makes it appear as if Fox anchor Chris Wallace is endorsing Carnahan. It wants an order barring Carnahan’s campaign from running the ad. “We believe we have the right to make sure voters see our ad,” Carnahan campaign chief Mindy Mazur wrote in an email to supporters Thursday, according to the St. Louis Post-Dispatch. “We’re not backing down, we’re not giving up. We’re staying on TV and fighting back. Make a donation now to help us fight back.”